assume cs: codesg, ds: datasg 

datasg segment 
	db 'welcome to masm!';用si和di实现将字符串‘welcome to masm！
	db '................'
datasg ends

codesg segment 
	start:	mov ax,datasg 
			mov ds,ax 
			mov si,0
			mov di,16

			mov cx, 8
	s:		mov ax, 0[si]  ;[0 + si]
			mov [di], ax ;[16 + si] 使用[bx +idata]方式代替di，使程序更简洁
			add si, 2 
            add di, 2 
			loop s 
			
			mov ax, 4c00h 
			int 21h 
codesg ends 
end start